ValueID bigint // (identity) item ID
GroupID bigint // group ID
Value int // item value
Created datetime2 // item created

GroupID bigint
FirstId bigint // from this ID (first in GID with Value ordered by Date)
LastId bigint // to this ID (last in GID with Value ordered by Date)
Value int // all share this value
Count // and this many occurrences (number of items between FirstID and LastId)